I disagree
I think to be able to utilize the total advantage of the 357 in a carbine you should go with the powerful loads of the 357 for the carbine, but if you love your hand gun you will not do that. Pretty simple[/QUOTE
The main advantage will be with practice ammo, which could be used in both the carbine as well as the pistol. You are correct that you would not want to fire a lot of “heavy magnum” loads in the handgun, but the bulk of ammo fired would most likely be mild practice ammo. Having the same caliber reduces the cost of shooting. Hopefully, less expensive ammo will translate into more time spent shooting, thus making you a better shot, and you can have more fun in the process. This is especially true if you hand load. One set of dies instead of two. One box of bullets instead of two. One can of powder… You get my point.